Masking plus refinement: A two-stage method for unsupervised few-shot learning
摘要
Unsupervised few-shot learning (UFSL) is a special scenario of few-shot learning, where the training data are unlabeled. The main challenge of UFSL is to learn a good representation for obtaining similarity relations without the benefit of supervision. We propose a two-stage approach, named Masking Plus Refinement (MPR), to learn and enhance the similarity measurement in steps. In stage one, we obtain high-quality image representations through masked image reconstruction and numerically illustrate that the masking image operation helps overcome the overfitting problem of large models in few-shot learning. In stage two, we use the combination of metric loss and feature-invariant loss to refine the similarity measurement. Experimental results show that our MPR outperforms the state-of-the-art UFSL methods by 2%-4% in a 5-way 1-shot setting on the mini-ImageNet and tiered-ImageNet benchmarks while also achieving better results on higher-resolution images.